The present invention relates generally to coatings for glass substrates. More specifically, the present invention relates to glass substrate coatings which exhibit low emissivity (so-called xe2x80x9clow-Exe2x80x9d coatings) and substantially no color characteristics.
Low-E coatings for glass are well known. In this regard, commonly owned U.S. Pat. Nos. 5,344,718, 5,425,861, 5,770,321, 5,800,933 (the entire content of each being incorporated expressly herein by reference) disclose coatings formed of a multiple layer coating xe2x80x9csystemxe2x80x9d. Generally, such conventional multiple layer low-E glass coatings have a layer of a transparent dielectric material (e.g., TiO2, Bi2O3, PbO or mixtures thereof) adjacent the glass substrate and a sequence of multiple layers of, for example, Si3N4, nickel (Ni), nichrome (Ni:Cr), nitrided nichrome (NiCrN) and/or silver (Ag). These conventional low-E coatings are, moreover, heat-treatablexe2x80x94that is, the coating is capable of being subjected to the elevated temperatures associated with conventional tempering, bending, heat-strengthening or heat-sealing processes without significantly adversely affecting its desirable characteristics.
While the conventional low-E coating systems disclosed in the above-cited U.S. patents are satisfactory, there exists a continual need to improve various properties of low-E coating systems generally. For example, continued improvements in the durability and/or color (or more accurately, lack of color) characteristics in low-E glass coatings are desired. Improvements in such characteristics are important to ensure that the coatings retain their low-E property for prolonged periods of time (even after being subjected to potentially abrasive environment encountered during the manufacturing processxe2x80x94e.g., the washing and cutting of glass articles having such low-E coatings) and have the desired light transmission properties. It is toward fulfilling such needs that the present invention is directed.
Broadly, the present invention is embodied in low-E glass coated glass articles comprised of a glass substrate and a multiple layer coating on a surface of the glass substrate, wherein the coating includes a layer of a transparent dielectric material adjacent the surface of the glass substrate, a layer of nitrided nichrome, and a layer of silver which is sputter coated onto the glass substrate in a nitrogen-containing atmosphere. Most preferably, the coating further includes a layer of silicon oxynitride interposed between the layer of dielectric material and the layer of nitrided nichrome.
These and other aspects and advantages will become more apparent after careful consideration is given to the following detailed description of the preferred exemplary embodiments thereof.